In recent years, the printing electronics technology has been developed quickly, and has covered the domains including printed circuits, organic electronic elements/components, transistors, display panels, sensors, photoelectric tubes, batteries, illuminators, conductors, and semiconductors, etc. A critical material in the printing electronics technology is electronic ink, in which electrically conductive ink is the most common and fundamental electronic ink, and the quality of electrically conductive ink has a decisive influence on the performance of printed electronic components. As an important electrically conductive packing material at present, nano-silver has become one of the hot spots in the research and development in the electrically conductive ink field globally.
At present, most nano-silver electrically conductive ink products that have been developed and are available in the market are water-based electrically conductive ink products and solvent-type electrically conductive ink products. Since the principal ingredient in water-based electrically conductive ink is water, the volatilization rate of the water-based electrically conductive ink is very low, and circuits printed with water-based electrically conductive ink are not easy to dry. Consequently, the bearing medium must have special coating; electronic circuits prepared with water-based electrically conductive ink have poor weather resistance, and it is difficult to maintain long-term performance stability of such electronic circuits in humid environments. Solvent-type nano-silver electrically conductive ink products mainly employ long-chain alkyl acids (e.g., dodecyl acid, hexadecyl acid), long-chain alkylamines (e.g., laurylamine, hexadecylamine), and long-chain alkyl benzene sulfonic acids (e.g., dodecylbenzene sulfonic acid) as the coating agent. Such electrically conductive ink products prepared with nano-silver as the electrically conductive packing material mainly employ benzenes (e.g., methyl benzene, dimethyl benzene) and alkanes (n-hexane, cyclohexane, and tetradecane, etc.) as the solvent. However, the most severe drawback among such electrically conductive ink products is severe environmental pollution, because the volatile organic content in the ink is very high. In view of environmental protection, the application of such electrically conductive ink products will be restricted gradually; in addition, since an Xaar or Spectra inkjet head is used in the printing process, most circuits prepared with such solvent-type electrically conductive ink products have low accuracy.
Therefore, it is of great research significance and potential market value to develop an environment-friendly, highly accurate, and weather-resistant nano-silver dispersible in weak solvent (eco-solvent), and an electrically conductive ink prepared from the same.